Optical device having light sensor employing horizontal electrical field

Abstract

The device includes an optical waveguide on a base. The waveguide is configured to guide a light signal through a light-transmitting medium. A light sensor is also positioned on the base. The light sensor including a ridge extending from slab regions. The slab regions are positioned on opposing sides of the ridge. A light-absorbing medium is positioned to receive at least a portion of the light signal from the light-transmitting medium included in the waveguide. The light-absorbing medium is included in the ridge and also in the slab regions. The light-absorbing medium includes doped regions positioned such that an application of a reverse bias across the doped regions forms an electrical field in the light-absorbing medium included in the ridge.

1. An optical device, comprising:
 a waveguide on a base, the waveguide configured to guide a light signal through a light-transmitting medium; and 
 a light sensor positioned on the base,
 the light sensor including
 a ridge extending from slab regions, the slab regions being on opposing sides of the ridge, 
 a light-absorbing medium positioned to receive at least a portion of the light signal from the light-transmitting medium in the waveguide, 
 the light-absorbing medium being included in the ridge and also in the slab regions, 
 the light-transmitting medium and the light-absorbing medium being different materials, 
 the light-absorbing medium including doped regions positioned such that an application of a reverse bias between the doped regions forms an electrical field in the light-absorbing medium included in the ridge. 
 
 
 
     
     
       2. The device of  claim 1 , wherein the doped regions are positioned on opposing sides of the ridge. 
     
     
       3. The device of  claim 1 , wherein the light-absorbing medium included in each slab region is continuous with the light-absorbing medium included in the ridge. 
     
     
       4. The device of  claim 1 , wherein the light-absorbing medium included in each slab region is continuous with the light-absorbing medium included in the ridge. 
     
     
       5. The device of  claim 1 , wherein one or more of the doped regions is included in both the ridge and one of the slab regions. 
     
     
       6. The device of  claim 1 , wherein one or more electrical contacts is positioned on the light-absorbing medium included in one of the slab regions. 
     
     
       7. The device of  claim 1 , wherein electrical contacts are each positioned on the light-absorbing medium included in one of the slab regions such that the ridge is positioned between the electrical contacts. 
     
     
       8. The device of  claim 7 , wherein each electrical contact contacts the light-absorbing medium. 
     
     
       9. The device of  claim 1 , wherein at least a portion of the electrical field can form on a path from one of the slab regions, through light-absorbing medium under the ridge, and then to another one of the slab regions without entering the light transmitting medium. 
     
     
       10. The device of  claim 1 , wherein the light-transmitting material is between the light-absorbing medium included in the ridge and the base. 
     
     
       11. The device of  claim 1 , wherein the light-transmitting material is between the light-absorbing medium included in the slab regions and the base. 
     
     
       12. The device of  claim 1 , wherein the light-transmitting material is between the light-absorbing medium included in the ridge and the base and also between the light-absorbing medium included in each of the slab regions and the base. 
     
     
       13. The device of  claim 1 , wherein the light-absorbing medium included in the ridge has a top side between lateral sides and each of the doped regions contacts one of the lateral sides. 
     
     
       14. The device of  claim 1 , wherein a portion of the light-absorbing medium included in the ridge is between doped regions and is undoped. 
     
     
       15. The device of  claim 1 , wherein the light-absorbing material includes germanium. 
     
     
       16. The device of  claim 1 , wherein the light-transmitting medium and the light-absorbing medium contact one another at an interface, the interface being configured such that the light signal travels through the interface, the interface being at a non-perpendicular angle relative to a direction of propagation of the light signals through the waveguide at the interface. 
     
     
       17. The device of  claim 16 , wherein the angle is between 80° and 85°.